62k

1985 TPI,383, previously passed inspection but did not this year. Scanning found trouble code 52 - calpak missing. Replaced calpak, no help. Secondly in checking o2 sensor I'm getting a .425 voltage from ecm to o2 sensor. According to Motorbook's Chev fuel injection between .3 to .6 volts indicate a bad ecm.....Replaced the ecm with a Mid America rebuilt . Slightly different reading but still between .3 and .6. O2 ground wire is good, ground straps replaced, fuses replaced, pins on prom and calpak are good, o2 is new. I mean what else is there?????????????Who knows how to check ecm's? As you can see, I could use some help......

scorp508

At idle your O2 should cycle through .999 to .0 over and over again. Hmm.....

MrNuke

What ecm is on that car? Stock '85's didnt have a calpack.

scorp508

What did they have?

MrNuke

A simple chip nothing else... calpack is the little board with the chip piggy backed on it..

scorp508

I know that, but the calpack also has the "other" chip in it with the limp home information. Thats why you still attach your original calpack to 1/2 of those EPROM adapters like Craig Moates makes. Was the 2nd chip in there too? They soldered on?

MrNuke

The 2nd chip must be soldered to the ecm inside then.

To replace chips on an '85 is just a cheesy chip. Gotta be real carefull not to screw the contacts/legs up when you put it in or pull it out..


[Modified by MrNuke, 7:50 PM 8/13/2003]

62k

The larger chip in the ecm is the prom. The second chip is smaller and is designated as the calpak serial number 16042437. Of main concern however is why is it not going into closed loop???????

frank moran

what kind of scanner are you using, auto xray will give you that cal pac message and it is not the problem, any other codes, check eng light on????that ecm has a prom in it

frank moran

ps, one other thing, that 85 has a burn off module behind the bread box, be sure it is going through the burn off cycle when you shut it down, see if the wires light up in the MAF sensor??? mine ran very rich, heavy fuel smell, burn off was not working ........

62k

You're correct , I am using an EZ Link by Auto Xray.It seems to be accurate. I am not getting a check engine light however.

62k

Interesting, but I don't have that problem. I'm absolutely certain that the ecm is not allowing me to go into closed loop.

LaVidaLoca

I use an AutoXray on my 85 and have also had the Calpak code show up. A good Vette mechanic here checked it out with his professional equipment and found no problem, so I just ignore it.

Also, on my 85 the AC/Requested, Park/Neutral detected, Block Learn, Cross Count and MAT do not read correctly. If I configure the scanner to VIN code L instead of 8 then I get correct readings on AC/Requested, Park/Neutral detected, Block Learn, and Cross Count. But still no MAT. Also, with it set for VIN code L it does not read all of the original information. So I go back and forth.

Been exchanging messages with the tech department at AutoXray and so far they have not resolved the issue.

One issue with Closed loop is the temperature of the engine. How warm is your engine when you are testing it?

MtlSphere

What does it look like? I had my dash apart and the bread box out. I replaced my ecm and had to replace two chips...large one I assumed was the prom...didn't have a clue about the smaller one but switched it anyway. The fuel pump prime started working again as well as a increased drivability...but...I get that rich smell too... :seeya

Update...the MAF burnoff is working...how cool is that?! I used a mirror and while it was running gently disconnected the maf from the air cleaner ducting and put a mirror at an angle so I could see the front of the MAF from the driver seat and turned off the ignition...seconds later...light show!

When I was in the dash I thought I found the burnoff module...another black box about the size of a pack of cigarettes with a wiring harness attached. It wasn't mounted to anything (previous owners handy work) and I couldn't see where it might belong so it's snugged in there loosely. It still works!


[Modified by MtlSphere, 6:04 AM 8/14/2003]

frank moran

the burn off mod is a silver box about the size of a cig pack, it is behind the bread box... if it is working not need to pull it apart..

62k

Temperature. I had a 175 degree thermo to accomodate my TPS prom so I changed to a 185 - no help. The engine need only to be 140 to go into closed loop. Again, I'm getting a .425 volt reading with the ignition FROM THE ECM TO THE o2 sensor instead of the other way around. There should be no voltage coming from the ecm. This is a Mid America rebuilt could it be defunct as well????? Anyone out there know of someone or company that works on ecm's Appreciate the info thus far...thanks.

Bluevette85

That box is likely the Theft Deterent Module.

Going into closed loop is a function of several parameters. Time and temp are two of them. There are two temperature sensors. The sensor between cylinders 1+3 is for the dash display only. The sensor the ecm uses is in front of the intake manifold next to the cold start injector switch. Your scan tool reads the Intake manifold sensor. I have the parameters for going into closed loop read from the stock chip at home and I will post them tonight.

Gregory VanLare

I had the same problem and couldn't figure it out. It was pinging horribly under hard load but ran well otherwise. The timing was way off and since then has been pretty good. I've encountered some other issues in the last week with an ESC error which is odd, I drive 15K every summer and have had to replace one twice, once last year and once the year before!! Something else must be going on to cause that! Good luck I know I need it!